Generic Airfoil Trailing-Edge Noise Prediction using Stochastic Sound Sources from Synthetic Turbulence

Abstract

A Computational Aeroacoustic (CAA) study is conducted for the simulation of broad-
\nband trailing-edge noise radiated from a NACA0012 airfoil and a cambered non-symmetrical
\nDU96 airfoil for different 
\now conditions. The chosen simulation approach uses a Reynolds
\nAveraged Navier-Stokes (RANS) solution to describe the turbulence around the airfoil.
\nWith a stochastic method time resolved synthetic turbulence 
\nuctuations are derived which
\nthen describe the unsteady sound sources used for acoustic perturbation equations (APE).
\nThe simulated broadband noise spectra are evaluated for different sets of input parameters
\nto determine the sensitivity of the used method towards these parameters. Calculated
\nvalues are compared to available measurement data to validate the underlying assumptions
\nand to give advices on the best practice settings. It is essential for any proper realization of
\nsound sources from a stochastic method that the RANS turbulence statistics are accurately
\nrealized. A length scale smoothing procedure is presented which remedies the problem of
\nspurious peaks in the realized turbulence statistics. A study is pursued regarding the tur-
\nbulent energy spectra realized by the stochastic turbulence reconstruction. Two different
\nspectra (Gauss and Liepmann) are analyzed. A positive effect of higher energy levels of
\nthe Liepmann spectrum in certain frequency ranges on the simulated sound field can be
\nshown.